Laptop Won't Start Up

Ive got a problem with my laptop. I just turned it on, and it goes to a black screen that says something like Windows apologizes for any inconvinience but it couldnt start up properly. Then it gives me different options on how to start up, which are:

- Safe Mode
- Safe Mode with Networking
- Safe Mode with Command Prompt
- Last Known Good Configuration
- Start Normally

I have tried all of these options and none of them work. Some of them restart the laptop, and some of them go to a blue screen which says the following file is absent or corrupt. The file is

systemroot/system32/config/SOFTWARE

I really need my laptop back to normal because I have alot of important things on it so any help would be great, thanks.

Are you running XP or windows vista?

The last time this happend to me
i had to reformatt everything n install fresh copy of windows

But if your using vista then itl store your files in a folder called Windows.old
which will save your work etc but your programs will go

If using XP then only thing you can do is start in safe mode n hope you can back up your work

Might wanna ask someone else on here. Because im no expert :P

You said none of then work?

And it says that file is corrupted? Your laptop came with a Windows Xp or Vista Restore disk right? Use that and any instructions that came with it ;)

If you need any more help just ask.